Pawl-and-ratchet mechanism.



W. SYLVESTFR.

PAWL AND RATCHET MECHANISM.

APPLICATION FILED OCT. 30. 1913.

ii i.

Patented Feb. 29, 1916.

4 SHEETSSHEET I.

W. SYLVESTER.

PAWL AND RATCHET MECHANISM.

APPLICATION FILED OCT. 30,1913. LWS Q5, Patented. Feb. 29,1916.

4 SHEETSSHEET 2- W. SYLVESTER.

v 'PAWL AND RATCHET MECHANISM.

APPLICATION FILED OCT. 30, 1913. 1,173,325. Patented Feb. 29, 1916.

4 SHEETSSHEET 3- W. SYLVESTER.

PAWL AND RATCHET MECHANISM.

APPLICATION FILED OCT. 30. 1913.

1,173,325., r Patented Feb. 29, 1916.

4 SHEETS-SHEET 4.

' WALTER SYLVESTER, OF TUNSTALL, STOKE-UPON-TRENT, ENGLAND.

PAWL-AND-RATCHET MECHANISM.

peciflcation of Letters Patent.

Patented Feb. 29, 1916.

Application filed October 30, 1913. Serial No. 798,318.

To all whom it may concern:

Be it known that I, WALTER SYLvEs'rER, a subject of the King of GreatBritain and Ireland, and resident of Tunstall, Stokeupon- Trent,Stafford, England, have invented certain 'new and useful Improvements inor Applicable to Pawl-and-Ratchet Mechanism, of which the following is aspecification.

This invention relates to improvements in lifting, hauling or strainingappliances of the kind in which a lever andpawls are used in conjunctionwith a toothed wheel or wheels to operate a drum, pulley, or chain blockwheel. I

The objects of the improvements are, first, to enable the reversemovement of said appliances to be effected by a simple adjustment whichpermits of the operating lever being worked in a similar manner eitherwhen hauling or lowering, the lowering or releasing being efi'ectedtooth by tooth; second, to provide means whereby the coils of rope,cable, chain, or the like may be kept tight and even on the drum orpulley; third, to provide means for preventing the drum or pulley beingunwound too far so as to cause damage to the rope or cable by thebackward bending action whichmay result; and, fourth, to provide meansfor enabling any ordinary mechanic to replace the old rope with a newone.

The objects are attained by the mechanism illustrated in theaccompanying drawings in which the improvements are shown in connectionwith a drum suitable for use with a flexible wire rope or the like andto which drum are attached two side plates or disks having ratchet teethon their periphcries.

F igure 1 is a front side elevation showing the pawls engaging with theratchet teeth when about to wind the rope or cable upon the drum thereversing mechanism being out of actlon until it is required to lower orrelease the load. Fig. 2 is a plan of Fig. 1 looking from the underside.Fig. 3 is a sectional side elevation of the lower portion 0 Fig. 1showing the reversing mechanism in action. Fig. 4 is a similar view toFig. 3 showing the position of the lever at the beginning of thelowering stroke. Fig. 5 is a sectional side elevation of the drumshowing the method of attaching the end of the rope or cable to theinside of the drum. Figs. 6 and 7 are illustrative of a modified form ofrope or cable securing means. Fig. 8 1s a cross-sectional elevation ofthe upper portion of Fig. 1 showing position of rope cap and the stopwheels, which latter are also shown in broken lines in Fig. 5. Fig. 9 isan end elevation showing the means for keeping the rope even on thedrum.

Similar letters refer to similar parts throughout the several views.

The drum (1 and the toothed wheels or ratchet disks 6, b with pawls c, amounted between the side cheeks or plates (1, d are carried by the shaftor spindle e.

In carrying the present invention into practice a lever f, hereinafterreferred to as the reversing arm, fulcrumed at f, is fitted into theframe of the machine for the purpose of lifting the pawls 0, 0 out ofengagement with the teeth, as eachv pawl is alternately relieved of thepressure of the load upon it, and for the further purpose of alternatelyholding the said pawls free from the ratchet wheels until the latterhave retated sufliciently to allow one or other of the pawls to engagewith the next succeeding tooth. The arm f is provided with two studs orpins g, 9 or two pairs of studs, which engage with the inner surface ofthe pawls, while springs h, k serve to bear on the pawls and arm,respectively, to set up an opposing force between the pawls and arm, aswill hereinafter be more fully understood. To the stud g is connectedone end of the spring h and to the stud g is connected by means of thelink h, one end of the spring 72. while the other ends of said springsare respectively connected to the pawl fulcrums.

During the time that the machine is lifting or drawing a load thereversing arm is kept out of operation by a small eccentric cylinder 5carried by the spindle z". To the eccentric i is fitted a small handle2' by which the eccentric may be rotated when requiring to bring intoaction the reversing mechanism.

The method of unwinding is as follows f The handle i is turned roundfrom the posihandle j is moved backward in the direction of the arrow wthe pressure upon the retaining pawl c is removed, and the reversing arm7 immediately lifts the pawl. 0 out of its notch to hold it clear untilthe point of the back tooth has passed. As the handle j is moved forwardin the direction of the arrow y the projection or swelling 0 formed onthe inside of the pawl 0 comes into contact with the stud g and themovement exerted by the said projection, as the pawl c is drawn past thestud 9 causes the arm I to be forced toward the drum which thereforeremoves the outward force exerted upon the pawl e, and causes it to fallinto the next notchready to take the pressure of the load from the pawl0 as soon as the lever j shall have described the necessary are to allowthe drum to rotate sufficiently to bring the next tooth into contactwith the pawl 0.

It will be understood that one pawl can only be affected by thereversing arm 7 during the period that the other pawl is bearing thepressure of the load. As soon as the pawl a has taken the pressure fromthe pawl c the arm 7 immediately lifts the latter named pawl out of itsnotch or tooth and holds it clear until the pawl 0 has been movedbackward in the direction of the arrow as a sufficient distance to bringthe stud g from the raised portion 0 of the irregular profile, formed onthe inner surface of the pawl 0 to the depression a". \Vhen the stud ghas entered into the depression 0* the stud g comes into contact withthe bottom of the depression 0 formed in the pawl 0, see Fig. 4. Thisholds the stud 9 clear of the pawl c and allows said pawl to fall intothe next notch which it has now reached,

see Fig. 4. As soon as the pawl 0? reaches the next tooth the pressureof the load is removed from the pawl c to the pawl and the operation isagain repeated until the load has been sufliciently lowered or released.

In order that the coils of rope or cable shall wind evenly and keeptight upon the drum a, a plate or frame is is hinged upon a pin is, seeFigs. 1 and 9, and forced against the periphery of the drum by a springZ, while a roller m fitted to the plate'k serves to reduce friction onthe rope. When the rope or cable is being unwound quickly there is adanger, immediately the last coil is run off, of the rope or cable beingsubjected to a bending action which in time would seriously damage therope or cable. To prevent this toothed wheels 72., n similar to thoseused in the overwind actions of clocks, are mounted on the drum andframe respectively, see Fig. 5. The stop action of the wheels n, n isbrought about by the wheel 91 having a shallow notch n and the wheel 12.having one tooth a larger than the remaining teeth. The wheels are alsomade of suflicient size and pitch, proportionately, to

allow the drum to make the requisite number of revolutions before thelarge tooth n shall I engage with the shallow notch n to bring about thestoppage.

To enable an ordinary mechanic to replace the wire rope or cable, it isfitted and supplied with a cap or socket 0 made to the curvature ofdrum. The cap or socket is capable of being riveted, or otherwisesecured, to the drum at 0, and of abutting against a shoulder orprojection a on the drum. In a modification the cap or socket 0 may behinged to a spindle passing through the drum a, see Fig. 6. With thislast named method of attachment the fixing and detaching of the rope orcable will be greatly facilitated, and the stop wheels 11., 11, may bedispensed with.

The above described method of fixing the rope or cable also serves todistribute the weight of the load more equally upon each of the wiresconstituting the rope where there is a. weakness near the cap. Theobject is still further attained by capping the rope when the rope andcap are placed in the same curved position as it will occupy when fittedto the drum. It is also preferable that the wires of the rope be securedin the cap by a filling of white metal or other suitable alloy.

Although the use and application of a wire rope or cable is shown it isto be understood that a chain or the like may be employed in connectionwith the improvements.

What I claim is 1. In pawl and ratchet mechanism, a

frame, a ratchet wheel axially mounted in said frame, a. retaining pawland an actuating lever pivotally mounted insaid frame,

an advancing pawl pivotally connected to the operating lever, means forurging the pawls into engagement with the ratchet wheels, and means forretracting the advancing pawl, said means being controlled by theadvancing pawl so as to retract the retaming pawl when said advancingpawl is in engagement with the ratchet wheel.

2. In pawl and ratchet mechanism, a frame, a ratchet drum axiallymounted in said frame, a pawl pivoted on a stationary pivot, a secondpawl pivoted on a movable pivot, means for advancing and retracting saidmovable pivot, means for urging the pawls into engagement with theratchet drum, spring actuated means for retracting the second pawl atone end of its stroke, controlled by said pawl at the end of its stroketo retract the first pawl substantially as herein set forth.

3. In pawl and ratchet mechanism, a frame consisting of two flat plateslylng parallel to each other and at a slight d15- tance apart,cross-stays holding the plates securely to each other and at the reulred distance apart, a spindle extending rom plate to plate, a ratchetdrum rotatably mounted on said spindle, a lever handle pivotally mountedbetween the plates of the frame, a pawl also pivotally mounted betweenthe plates of the frame, a second pawl pivotally mounted on the leverhandle, and means for urging both pawls into engagement with the ratchetdrum, a spring actuated lever arm pivotally connected to the frameandinterconnected with the pawls for alternately retracting said pawls,substantially as herein set forth.

4. Pawl and ratchet mechanism comprising a frame, a ratchet drum axiallymounted in said frame, a pair of pawls adapted to engage the teeth ofthe ratchet drum, a lever handle pivotally secured to the said frame,one of the said pawls being pivotally mounted in the said handle and theother of said pawls being pivotally mounted in the said frame, a leverarm pivotally mounted in the frame and having lateral studs near itsfree end engaging one pawl, and further lateral studs near its pivotedend which engage the other pawl, a coiled wire spring encircling thepivot of each pawl, a link pivotally connecting the end of the saidlever arm to one end of the spring around the pivot of the lever handlepawl,the other end of the same spring urging the-pawl into engagementwith the ratchet drum and the ends of the spring around the pivot of theother pawl respectively pressing against said pawl and the lever arm,recesses in the before mentioned pawls to receive the lateral studs onthe pivoted lever, the recess in the pawl pivoted to-the operatinghandle being shaped to govern the action of the before mentioned pivotedlever upon the other.

pawl, substantially as herein set forth.

5. In pawl and ratchet mechanism, a frame consisting of two flat plateslying parallel to each other and at a slight distance apart, cross-staysholding the plates securely to each other and at the required distanceapart, a spindle extending from plate to pivotally connected to theframe and provided with lateral projections to contact with recesses inthe inner face of the pawls to alternately retract the same, a spindleand cam revolubly mounted in the said frame,

an operating handle for said spindle whereby the cam-may be turned inone direction to move the lever toward the ratchet drum, with its studsclear of the pawls to allow said pawls to act independently, or in theopposite direction to allow the lever arm to recede from the ratchetwheel and the studs approach the pawls to insure inter-actionsubstantially as herein set forth.

6. Pawl and ratchet mechanism comprising a frame a ratchet wheel axiallymounted in said frame, a pair of pawls adapted to engage the teeth ofthe ratchet drum, one of said pawls being pivotally connected to anoperating handle and having a recess on one of its faces, deeper at theend next the hub of the pawl than at the other end and the bottom faceof the recess being sloped and undulating, and means for retracting saidpawls which engage the said recess to govern the retraction of theretaining pawl substantially as herein set forth.

In witness whereof I have hereunto set my hand in the presence of twowitnesses.

WALTER SYLVESTER.

Witnesses: 1

v PERCY SYLVESTER,

PATTIE PLANT.

